The present invention generally relates to automobile exterior components, and more particularly, to an external component of a vehicle, such as a vehicle bumper, having energy absorbing structures disposed therein.
U.S. Pat. No. 5,683,782 discloses a process for producing a thermoplastic sandwich material that includes a cylindrical cell structure. Referring to FIG. 1 of U.S. Pat. No. 5,683,782, a greatly enlarged sectional representation of a honeycomb segment with a cover layer is shown. In accordance with the invention disclosed in this patent, a thermoplastic sandwich material is made from two outer reinforced thermoplastic skins with a cellular core at the center that is molded by a thermo-compression process. The skins are formed from polypropylene with continuous glass mats, or are formed by woven glass with polypropylene fibers. The content of U.S. Pat. No. 5,683,782 is incorporated by reference into this application as if fully set forth herein.
Thermoplastic sandwich materials, such as those disclosed in U.S. Pat. No. 5,683,782, have been utilized in a variety of different applications. For example, U.S. patent application Ser. No. 09/451,970, filed Nov. 30, 1999 discloses a method for molding an impact resistant automotive part, such as a bumper beam. A thermoplastic reinforced fiber structure at least partially forms a pair of attachment portions of the automotive part and continuously extends between the attachment portions to link the attachment portions. The content of the U.S. Ser. No. 09/451,970 patent application is incorporated by reference into this application as if fully set forth herein.
In another example, U.S. patent application Ser. No. 09/445,356, filed Dec. 10, 1999 discloses a method of making a composite panel that has a sandwich structure and that is provided with a hinge. The panel comprises a stack that includes at least a first skin of a reinforced thermoplastic material and a second skin of a thermoplastic material. The panel is formed by preheating the first and second skins to a softening temperature, and then pressing the stack of skins at a pressure that lies in a predetermined range. The content of the Ser. No. 09/445,356 patent application is incorporated by referenced into this application as if fully set forth herein.
Yet another exemplary use of thermoplastic sandwich material is disclosed in U.S. patent application Ser. No. 09/485,142, filed Feb. 4, 2000. This application discloses a method of making a reinforced composite panel of the sandwich type having a cellular-core. The content of the Ser. No. 09/485,142 application is incorporated by reference into this application as if fully set forth herein.
U.S. patent application Ser. No. 09/525,346, filed Mar. 15, 2000 discloses the utilization of thermoplastic sandwich material in a certain application. In particular, this application discloses a method and system for co-molding a thermoplastic material with a thermoplastic sandwich material to form a thermoplastic sandwich article. The article has a thermoplastic inner portion. The content of patent application Ser. No. 09/525,346 is incorporated by reference into this application as if fully set forth herein.
U.S. patent application entitled xe2x80x9cMethod and System For Molding Thermoplastic Sandwich Material and Deep-Drawn Article Produced Thereby,xe2x80x9d filed Mar. 15, 2000 discloses a method and system for molding a thermoplastic sandwich material to form a deep-drawn article. In particular, an inner portion of a blank of thermoplastic sandwich material is forced into a female die along a vertical axis to form a deep-drawn article. A step of clamping may be performed at a plurality of spaced outer portions of the blank immediately adjacent the female die. The content of the above-referenced xe2x80x9cMethod and Systemxe2x80x9d patent application is incorporated by reference into this application as if filly set forth herein.
As discussed above, thermoplastic sandwich materials are being used in a variety of different automobile applications. It should be noted that typical automobiles have a hard steel frame body which forms the skeleton of the car. The hard steel frame body is designed to meet various strength requirements necessary to protect the vehicle occupant from injury in a collision. To provide the interior of the car with an aesthetically pleasing appearance, automobiles are designed with interior components such as a dashboard, pillars, headliners, consoles and the like.
In the event of a vehicle collision, an occupant may be injured if he or she comes into contact with the automobile interior component that typically is rigidly connected to the hard frame body inside of the vehicle. To protect the occupant from the hard frame structure, a number of governmental regulations regarding safety requirements, such as the head impact collision requirement FMUSS201, have been promulgated. A number of automobile interior components that currently are on the market do not satisfy these requirements.
Various regulations also mandate that external components of the vehicle, such as the bumper, meet impact requirements with respect to the damage incurred under controlled collisions. In one specific test, the vehicle is driven into a fixed seven inch diameter pole at five miles per hour to assess damage to the bumper. Alternately, the vehicle may remain stationary and a pendulum may impact the vehicle bumper. In that regard, various known bumper systems have been proposed. U.S. Pat. No. 3,744,835 discloses a shock absorbing honeycomb cell bumper, which is constructed from plastic and is covered by a rubber shell. Such a construction, however, is difficult to work with and is fairly expensive to implement because the entire bumper is formed of the honeycomb cell material.
With respect to impact absorption, the weight of the vehicle is a significant factor. Some known bumper systems use a low-density foam between the bumper fascia and the bumper bar. Foam works for its intended purpose but as requirements become more stringent and as the weight of the vehicle increases, some manufactures have used foam of a higher density in an attempt to meet the impact requirements. However, use of higher density foams has not appeared to enable manufactures to meet the above-mentioned impact test. Additionally, use of higher density foam increases the manufacturing cost, and also increases the overall weight of the bumper.
It is desirable to provide an energy-absorbing bumper that is cost-effective, light-weight and absorbs energy during a collision without damage, and permits impact tests to be met.
The disadvantages of present bumper systems are substantially overcome with the present invention. More specifically, the bumper system according to one embodiment of the present invention includes an elongated beam configured to be operatively mounted to the frame of the vehicle. Also included is a foam portion that extends along a portion of the beam, and a fascia surrounding the foam portion. The fascia and the foam portion are operatively attached to the beam. The foam portion has a plurality of recesses formed therein which extend through a predetermined thickness of an inside portion of the foam portion. An integrated cylindrical cell matrix is disposed with the recesses and is configured to absorb energy resulting from impact force applied to an external portion of the bumper.